Nitrogen in Tires
Nitrogen has been used on giant off-highway tires, on aircraft tires, and on racing tires for many years.
Air is about one-fifth oxygen, and oxygen, especially at high temperatures and pressures, is a very reactive element. When oxygen reacts with things, the process is called oxidation. When oxidation is extremely rapid, the process is called “burning.” That’s one reason nitrogen is used in off-highway and aircraft tires. These tires run so hot they can actually catch on fire. Nitrogen doesn’t support combustion, so nitrogen-filled tires don’t add fuel to the flames. And, nitrogen helps prevent slower forms of oxidation too.
Air migrates through rubber. Tires can lose 2 psi per month as a result of air passing through their sidewalls – like a balloon that shrivels up, but much slower. And, when oxygen passes through rubber, it can come into contact with steel cords, causing them to rust too. Between aging rubber and corroding steel cords, oxygen reduces retreadability.
While both nitrogen and oxygen can permeate rubber, nitrogen does it much more slowly. It might take six months to lose 2 psi with nitrogen, compared to just a month with air.
The air around us is full of water vapor. Water vapor in compressed air acts as a catalyst, accelerating rust and corrosion. Water vapor also absorbs and holds heat. And, when it changes from liquid to vapor, water expands tremendously in volume. So, tires inflated with wet air tend to run hotter and fluctuate in pressure more.
Hope this helps.
Cheers!